In general, a roller shutter is designed to open or close a shutter in such a manner that a plurality of slats made from a narrow and longitudinal steel sheet or aluminum are continuously interconnected and wound on or unwound from a rotary shaft installed inside of a shutter box at the top of a door frame.
In a place such as a beach or a plain, a building wherein a shutter is installed might receive strong wind. At this time, the wind pressure resistance criteria of a typical slat is below 45 m/s. In case that a wind speed is over 45 m/s, the slat may be deformed by wind force, so the slat might be derailed from a guide rail, so the shutter might become impossible to be opened and closed.
Except for the above problem, when the shutter is deformed by means of an external impact, the shutter also might become impossible to be opened or closed.
Meanwhile, in case of the related roller shutter, when the slat is deformed by wind pressure or external impact, it needs to exchange the whole structure of a door unit of the shutter, which results in the increased exchanging cost and long repairing time.
Since the conventional roller shutter is formed in a complicated structure wherein many components are used, the manufacturing cost increases, and the productivity decreases.